Alpha olefins are important items of commerce. Their many applications include employment as intermediates in the manufacture of detergents, as precursors to more environmentally friendly refined oils, as monomers, and as precursors for many other types of products. One method of making alpha olefins is via oligomerization of ethylene in a catalytic reaction involving various types of catalysts and/or catalyst systems. Examples of catalysts and catalyst systems used commercially in the oligomerization of ethylene include alkylaluminum compounds, certain nickel-phosphine complexes, a titanium halide with a Lewis acid (e.g., diethylaluminum chloride), a selective 1-hexene catalyst system containing a chromium containing compound (e.g., a chromium carboxylate), a nitrogen containing ligand (e.g., a pyrrole) and a metal alkyl (e.g., alkylaluminum compounds), and a selective trimerization and/or tetramerization catalyst system using a metal complex of a compound having a diphosphinylaminyl group.
Several oligomerization catalyst systems to produce alpha olefins are based upon metal complexes of pyridine bis-imines and metal complexes of α-diimine compounds having a metal complexing group, among others. These catalyst systems typically use an organoaluminum compound (e.g., aluminoxane) as a component of the catalyst system for olefin oligomerization.
Applications and demand for olefins (e.g., alpha olefins) continue to multiply and competition to supply them correspondingly intensifies. Thus, additional novel and improved catalyst systems and processes for olefin oligomerization are desirable.